1. Field
The present invention related to an apparatus for heat treating glass substrates, and in particular to an apparatus that reduces particulate contamination of closely stacked glass sheets while performing a heat treating process.
2. Technical Background
The fusion draw process produces glass that has been cooled rapidly, particularly below the annealing point. As a result, compaction may occur during heat treatments subsequent to the initial manufacturing phase such as during an ion exchange processes. The consequence is un-acceptable dimensional change and undesirable, reduced compressive stress resulting from the chemical tempering. Thicker wall glass articles have been previously successfully heat treated in annealing lehrs, box kilns, ovens or other heat treatment equipment. To date, success with this process for thin glass sheets has not been achieved due to deformation, abrasion, contamination or other degradation of the glass surface.